There is a good deal on an Exo Terra 18" by 18" by 24" on Craigslist near me. Both my OBT and H. maculata will need to be upgraded from juvie to permanent adult enclosures soon. Is this size just too big for either species? Should I keep looking for a 12" by 12" by 12" or even 12" by 12" by 18" instead? Thoughts?